I'm a beginner using AI CS5.5, and trying to add straight lines to a drawing, using the line tool. They are angled about 30 degrees from horizontal, parallel to each other. Used 2pt and color for lines. Everything looks great in AI. When I export the drawing to PNG for insertion as an illustration into InDesign and scale down (45%) the drawing to fit the InDesign page, the once perfectly smooth and straight lines are wavy, almost zigzaggy, slightly distorted. Not a good result.

Is there a better way to draw straight lines that are on an angle in the drawing so that they are perfectly smooth, and when scaled retain their smooth straight look?

It's just the screen view that is jagged. You will find when it prints it will be correct. To see a more accurate version on your screen in InDesign, select your object and go to Object > Display Performance > High Quality Display

Thank you. Changing to high display made the view of the AI placed file much better! (The project is for a digital eBook, so printing is unlikely, and viewing on screen would be the primary way it is read.)